Some population parameters of Hippocampus guttulatus derived from 272 samples from the southeastern Black Sea coast of Turkey collected between 2009 and 2011 are presented. The majority of the samples was collected from trawl nets (95%), followed by gill nets (4%) and purse seine nets (1%). Mean lengths and weights were found to be 8.304 +/- 0.659 cm and 2.129 +/- 0.511 g, respectively, for females, and 8.319 +/- 0.714 cm and 2.182 +/- 0.574 g, respectively, for males. There were no significant differences between males and females. Length-weight relationship for both sexes was calculated as W=0.0079L(2.635) (r=0.835). This relationship was W=0.0076L(2.6545) (r=0.829, n=136) for females and W=0.0069L(2.7047) (r=0.881, n=136) for males. This study supports the previous findings obtained for length-weight relationships, length-frequency distribution and weight at length data in other seas. The results indicate that growth of seahorses (Hippocampus guttulatus) is lower in the Black Sea than the Aegean Sea of Turkey.